Communication unit

ABSTRACT

A communication unit includes the following elements. A first transmit circuit outputs a first signal or a second signal from a first input signal. A first amplifier amplifies the first signal and outputs a first amplified signal. A first signal generating circuit generates a third signal having a frequency higher than a frequency of the second signal, based on the second signal and a first reference signal. A first filter circuit receives the third signal and allows one of a frequency component representing a sum of the frequency of the second signal and a frequency of the first reference signal and a frequency component representing a difference therebetween to pass through the first filter circuit and attenuates the other one of the frequency components. A second amplifier amplifies the third signal output from the first filter circuit and outputs a second amplified signal.

This is a division of U.S. patent application Ser. No. 15/490,073 filedon Apr. 18, 2017, which claims priority from Japanese Patent ApplicationNo. 2017-001320 filed on Jan. 6, 2017, Japanese Patent Application No.2016-161203 filed on Aug. 19, 2016, and Japanese Patent Application No.2016-083714 filed on Apr. 19, 2016. The contents of these applicationsare incorporated herein by reference in their entireties.

BACKGROUND

The present disclosure relates to a communication unit. A mobileterminal using a communication network for cellular phones contains acommunication unit that sends and receives radio frequency (RF) signalswith a base station. Nowadays, for mobile terminals, communication unitssupporting multiple communication standards (multimode) and multiplefrequency bands (multiband) are mainly used.

For example, “Application Guide for Mobile Communication” InfineonTechnologies, pp 11 [searched on Mar. 29, 2016], the Internet <URL:http://www.infineon.com/dgdl/Infineon-App_Guide_Mobile_CommunicatioC-BC-v01_01-EN.pdf?fileId=db3a304334c41e910134f6522b346704>disclosesa communication unit including a circuit supporting the secondgeneration (2G) of wireless communication systems and a circuitsupporting the third generation (3G) and the fourth generation (4G) ofwireless communication systems.

BRIEF SUMMARY

As the next-generation communication standard for mobile terminals, thefifth generation (5G) of wireless communication systems is attracting alot of attention, and demand for communication units supporting, notonly 3G and 4G, but also 5G is increasing. In 5G, frequency bands (about15 to 90 GHz, for example) higher than those in 3G and 4G will probablybe used. If a circuit supporting 5G is designed in a similar manner tothat of 3G and 4G, the circuit configuration becomes more complicatedand more components are required.

The present disclosure has been made in view of this background. Thepresent disclosure provides a communication unit that supports a newcommunication standard substantially without necessarily the need ofadditional components.

According to a preferred embodiment of the present disclosure, there isprovided a communication unit including a first transmit circuit, firstand second amplifiers, a first signal generating circuit, and a firstfilter circuit. The first transmit circuit outputs a first signal or asecond signal from a first input signal. The first amplifier amplifiesthe first signal and outputs a first amplified signal. The first signalgenerating circuit generates a third signal having a frequency higherthan a frequency of the second signal, based on the second signal and afirst reference signal. The first filter circuit receives the thirdsignal and allows one of a frequency component representing a sum of thefrequency of the second signal and a frequency of the first referencesignal and a frequency component representing a difference between thefrequency of the second signal and the frequency of the first referencesignal to pass through the first filter circuit and attenuates the otherone of the frequency components. The second amplifier amplifies thethird signal output from the first filter circuit and outputs a secondamplified signal.

According to a preferred embodiment of the present disclosure, it ispossible to provide a communication unit that supports a newcommunication standard substantially without necessarily the need ofadditional components.

Other features, elements, characteristics and advantages of the presentdisclosure will become more apparent from the following detaileddescription of preferred embodiments of the present disclosure withreference to the attached drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates an example of the configuration of a communicationunit according to an embodiment of the disclosure;

FIG. 2 illustrates examples of the configurations of a signal generatingcircuit and a power amplifier module;

FIG. 3 illustrates an example of a state where transmit signals aregenerated from an intermediate frequency (IF) signal and local signals;

FIG. 4 illustrates another example of a state where transmit signals aregenerated from the IF signal and local signals;

FIG. 5 illustrates another example of the configuration of thecommunication unit shown in FIG. 1;

FIG. 6 illustrates another example of the configuration of thecommunication unit shown in FIG. 1;

FIG. 7 illustrates another example of the configuration of thecommunication unit shown in FIG. 1;

FIG. 8 illustrates another example of the configuration of thecommunication unit shown in FIG. 1;

FIG. 9 illustrates another example of the configuration of the signalgenerating circuit;

FIG. 10 illustrates another example of the configuration of thecommunication unit shown in FIG. 1;

FIG. 11 illustrates an example of the configuration of anothercommunication unit according to an embodiment of the disclosure;

FIG. 12 illustrates examples of the configurations of a signalgenerating circuit and a low-noise amplifier module;

FIG. 13 illustrates an example of a state where an IF signal isgenerated from amplified signals and local signals;

FIG. 14 illustrates another example of the configuration of thecommunication unit shown in FIG. 11;

FIG. 15 illustrates another example of the configuration of thecommunication unit shown in FIG. 11;

FIG. 16 illustrates an example of the configuration of anothercommunication unit according to an embodiment of the disclosure; and

FIG. 17 schematically illustrates an example of the circuit arrangementon a communication device substrate on which a communication unit of anembodiment is mounted.

DETAILED DESCRIPTION

An embodiment of the present disclosure will be described below withreference to the accompanying drawings. FIG. 1 illustrates an example ofthe configuration of a communication unit 100 according to anembodiment. The communication unit 100 is used in a mobile communicationdevice, such as a cellular phone, for sending and receiving varioussignals, such as sound and data signals, with a base station. Thecommunication unit 100 supports multiple communication bands(multimode). In this embodiment, the communication unit 100 supportsconventional communication standards and new communication standards. Inthis specification, the conventional communication standards(hereinafter called “conventional modes”) are communication standardsusing frequencies in the C band (about 4 to 8 GHz) or lower bands. The Cband is one of the microwave-frequency bands according to IEEE standards(hereinafter simply called “IEEE C band”, and the other bands will alsobe called likewise, “IEEE X band”, for example). Examples of theconventional modes are 2G, 3G, and 4G. The new communication standards(hereinafter called “new modes”) are communication standards usingfrequencies in the IEEE X band (about 8 to 12 GHz) or higher bands. Anexample of the new modes is 5G. The communication unit 100 may supportmultiple frequency bands (multiband) in each communication standard. Inthis embodiment, a new mode supports a low band (IEEE Ku band (about 12to 18 GHz band), for example), a middle band (IEEE Ka band (about 26 to40 GHz band), for example), and a high band (IEEE V band (about 40 to 75GHz band), for example).

The communication unit 100 supports both of uplink communication from amobile terminal to a base station and downlink communication from a basestation to a mobile terminal. For the sake of description, in thecommunication unit 100, the configuration corresponding to downlinkcommunication will be omitted, and the configuration corresponding touplink communication will be discussed.

As shown in FIG. 1, the communication unit 100 includes a radiofrequency integrated circuit (RFIC) 105, a signal generating circuit120, power amplifier modules 130 and 131, front-end circuits 140 and141, and antennas 150 and 151.

The RFIC 105 includes a transmit circuit 110. The transmit circuit 110(first transmit circuit) includes a baseband circuit 160 and a RFcircuit 170. The transmit circuit 110 may include plural transmitcircuits in accordance with the modulation method and the frequencyband.

The baseband circuit 160 modulates an input signal (first input signal),such as a sound or data signal, based on a modulation method, such asquadrature amplitude modulation (QAM), and outputs the modulated signal.In this embodiment, the modulated signal is output from the basebandcircuit 160 as IQ signals representing the amplitude and the phase on anIQ plane. The frequency of the IQ signals is about several megahertz toseveral hundred megahertz, for example.

The RF circuit 170 generates and outputs a transmit signal forperforming wireless communication or an intermediate frequency (IF)signal for generating a transmit signal, based on the IQ signals outputfrom the baseband circuit 160. More specifically, if the input signal isbased on a conventional mode, the RF circuit 170 outputs a transmitsignal TX1 (first signal). If the input signal is based on a new mode,the RF circuit 170 outputs an IF signal IF1 (second signal). The RFcircuit 170 calculates a transmit signal in the following manner, forexample. The RF circuit 170 combines an I signal and a carrier signal ina multiplier and also combines a Q signal and a signal 90° out of phasewith the carrier signal in a multiplier, and combines these compositesignals in a subtractor. The transmit circuit 110 may output thetransmit signal TX1 or the IF signal IF1 from the same terminal.

The IF signal IF1 may be a signal of a frequency (about 5 to 10 GHz, forexample) which is lower than the frequency (about 15 GHz or 28 GHz, forexample) of a transmit signal TX2 (third signal) and which can begenerated by the transmit circuit 110 supporting the conventional modes.It is thus possible to generate the transmit signal TX2 of a new mode byusing the transmit circuit 110 supporting the conventional modes,without necessarily providing an extra transmit circuit for a new modein the communication unit 100.

The signal generating circuit 120 (first signal generating circuit)receives the IF signal IF1 from the RF circuit 170 and generates thetransmit signal TX2, based on the IF signal IF1 and a local signal.Details of the configuration of the signal generating circuit 120 willbe discussed later.

The power amplifier modules 130 and 131 each amplify power of an inputtransmit signal to a level necessary for transmitting the signal to abase station. The power amplifier module 130 includes an amplifier(first amplifier), and amplifies the transmit signal TX1 in a frequencyband of a conventional mode and outputs an amplified signal TX1_amp(first amplified signal). The power amplifier module 131 includes anamplifier (second amplifier), and amplifies the transmit signal TX2corresponding to multiple frequency bands of a new mode and outputs anamplified signal TX2_amp. The power amplifier modules 130 and 131 mayeach include plural amplification paths for amplifying transmit signalsof multiple frequency bands. Details of the configuration of the poweramplifier module 131 will be discussed later.

The front-end circuits 140 and 141 each switch between a path forsignals to be transmitted to the base station and a path for signals tobe received from the base station. The front-end circuits 140 and 141also perform filter processing, and more specifically, filter processingon the amplified signals TX1_amp and TX2_amp respectively supplied fromthe power amplifier modules 130 and 131 and received signals RX1 and RX2respectively supplied from the antennas 150 and 151. The front-endcircuits 140 and 141 may include a duplexer, a switch circuit, and adiplexer, for example.

The antennas 150 and 151 respectively transmit the amplified signalsTX1_amp and TX2_amp output from the front-end circuits 140 and 141 andrespectively receive the received signals RX1 and RX2 transmitted fromthe base station.

The configuration in which the transmit signal TX2 of a new mode isgenerated and amplified in the communication unit 100 will be discussedbelow with reference to FIG. 2. For the sake of simple description, itis assumed that the communication unit 100 supports two frequency bandsof a new mode. However, this is only an example, and the communicationunit 100 may support one frequency band or three or more frequency bandsof a new mode.

It is now assumed that, as examples of two frequency bands, a transmitsignal of a transmit frequency of about 15 GHz included in the IEEE Kuband (about 12 to 18 GHz band) and a transmit signal of a transmitfrequency of about 28 GHz included in the IEEE Ka band (about 26 to 40GHz band) will be generated. It is also assumed that the transmit signalof one frequency band BAND_A is TX2 a, the transmit frequency of thistransmit signal is fTX2 a=about 15 GHz, the transmit signal of the otherfrequency band BAND_B is TX2 b, and the transmit frequency of thistransmit signal is fTX2 b=about 28 GHz. A detailed description of theconfiguration in which the transmit signal TX1 of a conventional mode isgenerated and amplified will be omitted.

FIG. 2 illustrates examples of the configurations of the signalgenerating circuit 120 and the power amplifier module 131.

The signal generating circuit 120 includes a synthesizer 200 and amultiplier 210.

The synthesizer 200 generates a local signal having a predeterminedfrequency. The synthesizer 200 may be constituted by a phase-locked loop(PLL) circuit. In this embodiment, the synthesizer 200 generates andoutputs a local signal La (first reference signal) (frequency fLa=about10 GHz) for generating a transmit signal in the frequency band BAND_A ora local signal Lb (second reference signal) (frequency fLb=about 23 GHz)for generating a transmit signal in the frequency band BAND_B.

The multiplier 210 combines the local signal La supplied from thesynthesizer 200 and the IF signal IF1 supplied from the RF circuit 170so as to generate a transmit signal TX2 a (third signal), and outputsit. Similarly, the multiplier 210 combines the local signal Lb suppliedfrom the synthesizer 200 and the IF signal IF1 supplied from the RFcircuit 170 so as to generate a transmit signal TX2 b (fourth signal),and outputs it. If the IF signal IF1 is not supplied to the multiplier210, the synthesizer 200 and the multiplier 210 may be turned OFF sothat a local signal and a transmit signal will not be generated. Thefrequencies of the signals generated by the multiplier 210 will bediscussed with reference to FIG. 3.

FIG. 3 illustrates an example of a state where the transmit signals TX2a and TX2 b are respectively generated from the IF signal IF1 and thelocal signals La and Lb. The multiplier 210 outputs a signal of afrequency representing the sum of the frequencies of the two signals andalso outputs a signal of a frequency representing the difference betweenthe frequencies of the two signals. That is, if the local signal La(frequency fLa=about 10 GHz) and the IF signal IF1 (frequency fIF=about5 GHz) are input, the multiplier 210 outputs signals including a signalMIX1 _(UP) having a frequency fLa+fIF=10+5=15 GHz and a signal _(MIX1) a_(DOWN) having a frequency fLa−fIF=10−5=5 GHz. In this embodiment, thesignal MIX1 a _(UP) of about 15 GHz is used as the transmit signal TX2a, and the signal MIX1 a _(DOWN) of about 5 GHz is an unwanted signal(also called an image signal).

Similarly, if the local signal Lb (frequency fLb=about 23 GHz) and theIF signal IF1 (frequency fIF=about 5 GHz) are input, the multiplier 210outputs signals including a signal MIX1 b _(UP) having a frequencyfLb+fIF=23+5=28 GHz and a signal MIX1 b _(DOWN) having a frequencyfLb−fIF=23−5=18 GHz. In this embodiment, the signal MIX1 b _(UP) ofabout 28 GHz is used as the transmit signal TX2 b, and the signal MIX1 b_(DOWN) of about 18 GHz is an image signal. The attenuation of the imagesignals MIX1 a _(DOWN) and MIX1 b _(DOWN) will be discussed later,together with an explanation of the configuration of the power amplifiermodule 131.

Referring back to FIG. 2, the power amplifier module 131 amplifies thetransmit signals TX2 a and TX2 b output from the signal generatingcircuit 120 and outputs amplified signals TX2 a_amp and TX2 b_amp. Thepower amplifier module 131 includes a switch circuit 220, filtercircuits 230 a, 230 b, 231 a, and 231 b, and amplifiers 240 a and 240 b.In this embodiment, a switch element 220 a, the filter circuits 230 aand 231 a, and the amplifier 240 a form an amplification path for thetransmit signal TX2 a of the frequency band BAND_A, while a switchelement 220 b, the filter circuits 230 b and 231 b, and the amplifier240 b form an amplification path for the transmit signal TX2 b of thefrequency band BAND_B. For the sake of simple representation, the otherelements forming the power amplifier module 131 (such as a bias circuitand a matching circuit) are not shown in FIG. 2.

The switch circuit 220 (second switch circuit) supplies only one of thetransmit signals TX2 a and TX2 b in the two frequency bands to theassociated amplification path and performs control so that the twoamplifiers 240 a and 240 b will not operate at the same time. The switchcircuit 220 includes the switch elements 220 a and 220 b. The switchelements 220 a and 220 b connect or disconnect the signal generatingcircuit 120 to or from the power amplifier module 131 in the individualamplification paths. When one of the switch elements 220 a and 220 b isON, the other one of the switch elements 220 a and 220 b is OFF. Whenone of the transmit signals TX2 a and TX2 b is supplied to theassociated amplification path, the other one of the transmit signals TX2a and TX2 b is not supplied to the associated amplification path. It isthus less likely that a transmit signal which may leak from oneamplification path will be input into the other amplification path. Thatis, the isolation between the amplification paths of the transmitsignals TX2 a and TX2 b can be enhanced.

With the above-described configuration, when signals in relatively closefrequency bands are generated in the signal generating circuit 120, itis less likely that one signal will influence the other signal as noise.More specifically, for example, the frequency of the signal MIX1 a _(UP)(about 15 GHz) generated as a transmit signal in the frequency bandBAND_A and the frequency of the MIX1 b _(DOWN) (about 18 GHz) generatedas a signal to be attenuated in the frequency band BAND_B are relativelyclose to each other (see FIG. 3).

The switch elements 220 a and 220 b may be constituted bymetal-oxide-semiconductor field-effect transistors (MOSFETs) or bipolartransistors, such as heterojunction bipolar transistors (HBTs). Switchelements 300, 620 a, 620 b, and 700, which will be discussed later, mayalso be constituted likewise.

The filter circuits 230 a and 230 b (first and second filter circuits)are filters for attenuating the above-described image signals MIX1 a_(DOWN) and MIX1 b _(DOWN). More specifically, among the signalsgenerated by the signal generating circuit 120, the filter circuit 230 aallows frequency components of the signal MIX1 a _(UP) to pass throughthe filter circuit 230 a and attenuates frequency components of thesignal MIX1 a _(DOWN). Among the signals generated by the signalgenerating circuit 120, the filter circuit 230 b allows frequencycomponents of the signal MIX1 b _(UP) to pass through the filter circuit230 b and attenuates frequency components of the signal MIX1 b _(DOWN).

The filter circuit 230 a may be a band pass filter circuit or a highpass filter circuit that allows the frequency components of the signalMIX1 a _(UP) (about 15 GHz) to pass through the filter circuit 230 a andattenuates the frequency components of the signal MIX1 a _(DOWN) (about5 GHz), which is lower than the frequency of the signal MIX1 a _(UP)(about 15 GHz) (see FIG. 3). Similarly, the filter circuit 230 b may bea band pass filter circuit or a high pass filter circuit that allows thefrequency components of the signal MIX1 b _(UP) (about 28 GHz) to passthrough the filter circuit 230 b and attenuates the frequency componentsof the MIX1 b _(DOWN) (about 18 GHz), which is lower than the frequencyof the signal MIX1 b _(UP) (28 GHz) (see FIG. 3).

Forming the filter circuits 230 a and 230 b as band pass filter circuitscan attenuate, not only the frequency components of the signals MIX1 a_(DOWN) and MIX1 b _(DOWN), but also a signal leaking from theamplification path in the other frequency band. The filter circuits 230a and 230 b can also attenuate harmonics of transmit signals.

The amplifiers 240 a and 240 b (second and third amplifiers)respectively amplify the transmit signals TX2 a and TX2 b output fromthe filter circuits 230 a and 230 b, and respectively output amplifiedsignals TX2 a_amp and TX2 b_amp (second and third amplified signals).The amplifiers 240 a and 240 b may be constituted by MOSFETs or bipolartransistors, such as HBTs. The amplifiers 240 a and 240 b may be eachconstituted by plural stages of amplifiers.

The filter circuits 231 a and 231 b attenuate harmonics of the amplifiedsignals TX2 a_amp and TX2 b_amp and noise caused by the amplifiers 240 aand 240 b. The filter circuits 231 a and 231 b may be band pass filtercircuits or low pass filter circuits.

The amplified signals TX2 a_amp and TX2 b_amp output from the poweramplifier module 131 are respectively transmitted from the antennas 151a and 151 b via the front-end circuits 141 a and 141 b.

In the communication unit 100 shown in FIG. 1 configured as describedabove, the transmit circuit 110 does not directly generate a transmitsignal in a frequency band of a new mode, but generates an IF signalinstead. Then, the signal generating circuit 120 generates a transmitsignal in a frequency band of a new mode. By using the transmit circuit110 supporting conventional modes, the communication unit 100 is able tosupport a new communication standard (new mode) substantially withoutnecessarily the need of additional components.

In this embodiment, the two antennas 151 a and 151 b are respectivelyprovided for the frequency bands BAND_A and BAND_B. Alternatively, asingle antenna may be used for all multiple frequency bands, and aswitch circuit included in a front-end circuit may switch between atransmit signal supplied to the antenna and a received signal suppliedfrom the antenna. The use of the single antenna for all multiplefrequency bands can reduce the size of a communication unit.

The combination of frequencies of transmit signals output from thecommunication unit 100 is not restricted to the above-describedcombination (about 15 GHz and 28 GHz). For example, frequencies (about28 GHz and 39 GHz) both included in the IEEE Ka band (about 26 to 40 GHzband) may be output from the communication unit 100. Such a case will bediscussed below with reference to FIG. 4. It is assumed that thetransmit signal of one frequency band BAND_C is TX2 c, the transmitfrequency of this transmit signal is fTX2 c=about 28 GHz, the transmitsignal of the other frequency band BAND_D is TX2 d, and the transmitfrequency of this transmit signal is fTX2 d=about 39 GHz.

FIG. 4 illustrates an example of a state where the transmit signals TX2c and TX2 d are generated from the IF signal IF1 and local signals Lcand Ld. In this embodiment, the synthesizer 200 generates and outputs alocal signal Lc (first reference signal) (frequency fLc=about 33 GHz)for generating a transmit signal in the frequency band BAND_C or a localsignal Ld (second reference signal) (frequency fLd=about 34 GHz) forgenerating a transmit signal in the frequency band BAND_D. The frequencyof the local signal Lc is relatively close to that of the local signalLd, and the two local signals Lc and Ld may be generated by theadjustment in the synthesizer 200, for example.

The multiplier 210 generates and outputs, from the local signal Lc(frequency fLc=about 33 GHz) and the IF signal IF1 (fIF=about 5 GHz),signals including a signal MIX1 c _(UP) having a frequencyfLc+fIF=33+5=38 GHz and a signal MIX1 c _(DOWN) having a frequencyfLc−fIF=33−5=28 GHz. Similarly, the multiplier 210 generates andoutputs, from the local signal Ld (frequency fLd=about 34 GHz) and theIF signal IF1 (fIF=about 5 GHz), signals including a signal MIX1 d _(UP)having a frequency fLd+fIF=34+5=39 GHz and a signal MIX1 d _(DOWN)having a frequency fLd−fIF=34−5=29 GHz.

The filter circuits 230 a and 230 b attenuate the image signals MIX1 c_(UP) and _(MIX1) d _(DOWN) output from the signal generating circuit120. More specifically, the filter circuit 230 a is a band pass filtercircuit or a low pass filter circuit that allows frequency components ofthe signal MIX1 c _(DOWN) (about 28 GHz) to pass through the filtercircuit 230 a and attenuates frequency components of the MIX1 c _(UP)(about 38 GHz), which is higher than the frequency components of thesignal MIX1 c _(DOWN) (about 28 GHz). The filter circuit 230 apreferably attenuates frequency components of the signal MIX1 d _(DOWN)(about 29 GHz) generated in the path of the frequency band BAND_D.

The filter circuit 230 b is a band pass filter circuit or a high passfilter circuit that allows frequency components of the signal MIX1 d_(UP) (about 39 GHz) to pass through the filter circuit 230 b andattenuates frequency components of the MIX1 d _(DOWN) (about 29 GHz),which is lower than the frequency components of the signal MIX1 d _(UP)(about 39 GHz). The filter circuit 230 b preferably attenuates thefrequency components of the signal MIX1 c _(UP) (about 38 GHz) generatedin the path of the frequency band BAND_C.

As described above, in the communication unit 100, the power amplifiermodule 131 includes the filter circuits 230 a and 230 b. This makes itpossible to use both of the frequency components representing the sum ofthe frequencies of the IF signal and a local signal and the frequencycomponents representing the difference between the frequencies of the IFsignal and the local signal as transmit signals.

The communication unit 100 may generate a transmit signal of an evenhigher frequency. For example, if the frequency of a transmit signal isabout 45 GHz included in the IEEE V band (about 40 to 75 GHz band), thesynthesizer 200 may generate a local signal of about 35 GHz, and the RFcircuit 170 may generate an IF signal of about 10 GHz (that is, anintegral multiple of the frequency at 5 GHz of the IF signal IF1). Themultiplier 210 generates and outputs signals including frequencycomponents representing the sum of the frequencies of the local signaland the IF signal (35+10=45 GHz) and frequency components representingthe difference between the frequencies of the local signal and the IFsignal (35−10=25 GHz). The filter circuit 230 b may be a high passfilter circuit or a band pass filter circuit that allows the frequencycomponents (about 45 GHz) to pass through the filter circuit 230 b andattenuates the frequency components (about 25 GHz). Then, a transmitsignal of about 45 GHz is generated. When a high-frequency local signalis used, it may leak from the signal generating circuit 120 and be inputinto the power amplifier module 131, which may cause noise. The filtercircuit 230 b thus preferably attenuates the frequency components (about35 GHz) of the local signal, in addition to the frequency components(about 25 GHz) representing the difference between the local signal andthe IF signal.

FIG. 5 illustrates another example of the configuration of thecommunication unit 100 (communication unit 100A) according to theembodiment. The communication unit 100A is different from thecommunication unit 100 shown in FIG. 1 in that it includes a switchelement 300 in addition to the elements forming the communication unit100.

The switch element 300 (first switch circuit) is disposed between thetransmit circuit 110 and the signal generating circuit 120, and connectsor disconnects the transmit circuit 110 to or from the signal generatingcircuit 120. More specifically, the switch element 300 is turned ON whenthe communication unit 100A generates a transmit signal in a frequencyband of a new mode, and the switch element 300 is turned OFF when thecommunication unit 100A does not generate a transmit signal in afrequency band of a new mode. It is thus less likely that, whenprocessing a transmit signal of a conventional mode and that of a newmode, a transmit signal of one mode will be input into the path of atransmit signal of the other mode. The switch element 300 may bedisposed within a RFIC 105A, as shown in FIG. 5, or may be disposedoutside the RFIC 105A.

FIG. 6 illustrates another example of the configuration of thecommunication unit 100 (communication unit 100B) according to theembodiment. The communication unit 100B is different from thecommunication unit 100 shown in FIG. 1 in that it includes a transmitcircuit 310, a power amplifier module 330, a front-end circuit 340, andan antenna 350 corresponding to a transmit signal TX3 in a frequencyband of a conventional mode, in addition to the elements forming thecommunication unit 100.

The transmit circuit 310 (second transmit circuit) modulates an inputsignal (second input signal), such as a sound or data signal, andoutputs a transmit signal TX3 (fifth signal).

The power amplifier module 330 includes an amplifier (fourth amplifier),and amplifies the transmit signal TX3 in a frequency band of aconventional mode and outputs an amplified signal TX3_amp (fourthamplified signal). The amplified signal TX3_amp output from the poweramplifier module 330 is transmitted from the antenna 350 via thefront-end circuit 340.

The detailed configurations of the transmit circuit 310, the poweramplifier module 330, the front-end circuit 340, and the antenna 350 aresimilar to those of the transmit circuit 110, the power amplifier module130, the front-end circuit 140, and the antenna 150 shown in FIG. 1, anda detailed explanation thereof will be omitted.

With this configuration, too, by using the transmit circuits 110 and 310supporting conventional modes, the communication unit 100B is able tosupport a new communication standard (new mode) substantially withoutnecessarily the need of additional components. The communication unit100B, which is capable of simultaneously transmit signals of multiplefrequency bands, is applicable to a mobile terminal supporting carrieraggregation, for example. The switch element 300 shown in FIG. 5 mayalso be used in the communication unit 100B. As shown in FIG. 6, thetransmit circuits 110 and 310 may be included in a single RFIC 105B.Alternatively, the communication unit 100B may include plural RFICs, andthe RFICs may include the respective transmit circuits 110 and 310.

FIG. 7 illustrates another example of the configuration of thecommunication unit 100 (communication unit 100C) according to theembodiment. The communication unit 100C is different from thecommunication unit 100 shown in FIG. 1 in that it includes a RFIC 105C,a transmit circuit 110A, a RF circuit 170A, and a signal generatingcircuit 120A, instead of the RFIC 105, the transmit circuit 110, the RFcircuit 170, and the signal generating circuit 120. More specifically,in the communication unit 100C, the synthesizer 200 is formed in theRFIC 105C.

The synthesizer 200 generates a local signal Le having a predeterminedfrequency and outputs it to the signal generating circuit 120A. Forexample, if the frequency of the local signal Le is about 23 GHz and thefrequency of the IF signal IF1 is about 5 GHz, the synthesizer 200generates a transmit signal of a transmit frequency of about 28 GHz (23GHz+5 GHz). The frequency of the local signal Le generated by thesynthesizer 200 is not restricted to 23 GHz. Adjusting of the frequencyof the local signal Le can generate transmit signals of various transmitfrequencies. Details of the generation of signals in the multiplier 210are similar to those in the communication unit 100, and a detailedexplanation thereof will be omitted.

With this configuration, too, by using the transmit circuit 110Asupporting conventional modes, the communication unit 100C is able tosupport a new communication standard (new mode) substantially withoutnecessarily the need of additional components. The switch element 300shown in FIG. 5 may also be used in the communication unit 100C.

FIG. 8 illustrates another example of the configuration of thecommunication unit 100 (communication unit 100D) according to theembodiment. The communication unit 100D is different from thecommunication unit 100C shown in FIG. 7 in that it includes a signalgenerating circuit 120B instead of the signal generating circuit 120A.The signal generating circuit 120B includes frequency multipliers 201and 202, in addition to the multiplier 210.

The frequency multipliers 201 and 202 multiply the frequency of thelocal signal Le received from the synthesizer 200 by a factor of N (N isa natural number) and output the multiplied local signal Le. In thisembodiment, both of the frequency multipliers 201 and 202 are frequencydoublers that double the frequency of the local signal Le. For example,if the frequency of the local signal Le is about 8.5 GHz and thefrequency of the IF signal IF1 is about 5 GHz, the frequency multipliers201 and 202 generate a transmit signal of a transmit frequency of about39 GHz (8.5 GHz×2×2+5 GHz). If the frequency of the local signal Le isabout 15.25 to 17.75 GHz and the frequency of the IF signal IF1 is about5 GHz, the frequency multipliers 201 and 202 generate a transmit signalof a transmit frequency of about 66 to 76 GHz (15.25 to 17.75 GHz×2×2+5GHz). The frequency multipliers 201 and 202 are not restricted to aparticular type, and may be constituted by a PLL circuit, for example.Details of the generation of signals in the multiplier 210 are similarto those in the communication unit 100, and a detailed explanationthereof will be omitted.

With this configuration, too, by using the transmit circuit 110Asupporting conventional modes, the communication unit 100D is able tosupport a new communication standard (new mode) substantially withoutthe need of additional components. The switch element 300 shown in FIG.5 may also be used in the communication unit 100D.

FIG. 9 illustrates another example of the configuration of the signalgenerating circuit 120 (signal generating circuit 120C). The signalgenerating circuit 120C includes an image rejection mixer. Morespecifically, the signal generating circuit 120C includes multipliers203 and 204, phase shifters 205 and 206, and an adder 207, in additionto the elements forming the signal generating circuit 120B.

The signal generating circuit 120C generates a transmit signal TX2 fromthe IF signal IF1 and the local signal Le. The operation of the imagerejection mixer will be discussed below. It is assumed that the angularfrequency of the IF signal IF1 is α, the angular frequency of a localsignal Lf obtained by multiplying the local signal Le in the frequencymultipliers 201 and 202 is β, the time is t, the angular frequency of atransmit signal to be generated is α+β, and the angular frequency of animage signal is α−β. For the sake of simple description, if theamplitude of each signal is 1,the IF signal IF1 is represented bycos(αt) and the local signal Lf is represented by cos(βt).

The IF signal IF1 is distributed to the multipliers 203 and 204. Thelocal signal Lf is also distributed to the multipliers 203 and 204. Inthis case, the distributed local signal Lf is directly output to themultiplier 203, while it is first output to the phase shifter 205 whichprovides phase lead to the local signal Lf by about 90 degrees and isthen output to the multiplier 204. The multiplier 203 multiplies cos(αt)and cos(βt) so as to generate a signal proportional tocos{(α+β)t}+cos{(α−β)t}. The multiplier 204 multiplies cos(αt) andsin(βt) so as to generate a signal proportional tosin{(α+β)t}−sin{(α−β)t}. The signal generated in the multiplier 204 isoutput to the phase shifter 206 which provides phase delay to the signalby about 90 degrees, and a signal proportional tocos{(α+β)t}−cos{(α−β)t} is generated. The signal output from themultiplier 203 and the signal output from the phase shifter 206 areadded in the adder 207. As a result, a signal proportional tocos{(α−β)t} (that is, an image signal) alone is rejected, while a signalproportional to cos{(α+β)t} (that is, the transmit signal TX2) alone isoutput.

With the above-described configuration, the signal generating circuit120C can generate frequency components representing the sum of thefrequencies of the IF signal IF1 and the local signal Lf and rejectfrequency components representing the difference therebetween. Thesignal generating circuit 120C is able to reduce the influence of noisecaused by the image signal to a smaller level than the signal generatingcircuit 120B. The above-configured signal generating circuit 120C isparticularly effective when a transmit signal of a relatively highfrequency, such as 60 GHz or higher, is generated in the communicationunit 100D because the attenuation of an image signal using a filtercircuit is difficult.

FIG. 10 illustrates another example of the configuration of thecommunication unit 100 (communication unit 100E) according to theembodiment. The communication unit 100E is different from thecommunication unit 100 shown in FIG. 1 in that it includes a RFIC 405, apower amplifier module 430, a front-end circuit 440, and an antenna 450that support a wireless local area network (LAN), such as Wi-Fi, inaddition to the elements forming the communication unit 100.

The RFIC 405 includes a transmit circuit 410 (first transmit circuit)supporting a wireless LAN. In this embodiment, a RF circuit 170Bincluded in the transmit circuit 410 generates an IF signal IF1 andoutputs it to the signal generating circuit 120. The frequency of the IFsignal IF1 may be about 5 GHz, for example. That is, the IF signal IF1may be generated by the RFIC 105 supporting conventional modes, such as3G and 4G, or by the RFIC 405 supporting a wireless LAN shown in FIG.10. The detailed configurations of the power amplifier module 430, thefront-end circuit 440, and the antenna 450 are similar to those of thepower amplifier module 130, the front-end circuit 140, and the antenna150, and a detailed explanation thereof will be omitted.

With this configuration, too, by using the transmit circuit 410supporting a wireless LAN, the communication unit 100E is able tosupport a new communication standard (new mode) substantially withoutthe need of additional components. The switch element 300 shown in FIG.5 may also be used in the communication unit 100E. As the frequency bandof 5G, it is possible that a frequency band near 5 GHz be also used. Theuse of such a frequency band may be handled by replacing the signalgenerating circuit 120 by a simple switch.

FIG. 11 illustrates an example of the configuration of a communicationunit 500 according to an embodiment of the disclosure. For the sake ofdescription, in the communication unit 500, the configurationcorresponding to uplink communication will be omitted, and theconfiguration corresponding to downlink communication will be discussed.The same elements as those of the communication unit 100 shown in FIG. 1are designated by like reference numerals, and an explanation thereofwill be omitted.

As shown in FIG. 11, the communication unit 500 includes a RFIC 505, areceive circuit 510, a signal generating circuit 520, and low-noiseamplifier modules 530 and 531, instead of the RFIC 105, the transmitcircuit 110, the signal generating circuit 120, and the power amplifiermodules 130 and 131 shown in FIG. 1.

The low-noise amplifier modules 530 and 531 respectively amplify powerof signals received by the antennas 150 and 151 and input from thefront-end circuits 140 and 141 to a level necessary for demodulating thesignals. The low-noise amplifier module 530 includes an amplifier (firstlow-noise amplifier), and amplifies a received signal RX1 (sixth signal)in a frequency band of a conventional mode and outputs an amplifiedsignal RX1_amp (fifth amplified signal). The low-noise amplifier module531 includes an amplifier (second low-noise amplifier), and amplifies areceived signal RX2 (seventh signal) corresponding to multiple frequencybands of a new mode and outputs an amplified signal RX2_amp. Thelow-noise amplifier modules 530 and 531 may each include pluralamplification paths for amplifying received signals of multiplefrequency bands. Details of the configuration of the low-noise amplifiermodule 531 will be discussed later.

The signal generating circuit 520 (second signal generating circuit)receives the amplified signal RX2_amp output from the low-noiseamplifier module 531, amplifies an IF signal IF2 generated based on theamplified signal RX2_amp and a local signal, and outputs an amplifiedsignal IF2_amp. Details of the configuration of the signal generatingcircuit 520 will be discussed later.

The RFIC 505 includes the receive circuit 510. The receive circuit 510(first receive circuit) includes a RF circuit 570 and a baseband circuit560.

The RF circuit 570 generates IQ signals, based on the amplified signalRX1_amp output from the low-noise amplifier module 530 or the amplifiedsignal IF2_amp output from the signal generating circuit 520, andoutputs the IQ signals. The receive circuit 510 may receive theamplified signal RX1_amp or the amplified signal IF2_amp from the sameterminal.

The baseband circuit 560 demodulates the IQ signals based on themodulation method, such as QAM, and outputs an output signal (firstoutput signal), such as a sound or data signal. The receive circuit 510may include plural receive circuits in accordance with the demodulationmethod and the frequency band.

The configuration in which the received signal RX2 of a new mode isreceived and amplified in the communication unit 500 will be discussedbelow with reference to FIG. 12. As in the case of uplink communication,a circuit corresponding to the IEEE Ku band as an example of thefrequency band BAND_A of a new mode and to the IEEE Ka band as anexample of the frequency band BAND_B of a new mode is shown. However,the configuration of the communication unit 500 is not restricted tothis example. It is assumed that the received signal of the frequencyband BAND_A is RX2 a, the receive frequency of this received signal isfRX2 a=about 15 GHz, the received signal of the frequency band BAND_B isRX2 b, and the receive frequency of this received signal is fRX2 b=about28 GHz. A detailed description of the configuration in which thereceived signal RX1 of a conventional mode is received and amplifiedwill be omitted.

FIG. 12 illustrates examples of the configurations of the low-noiseamplifier module 531 and the signal generating circuit 520.

The low-noise amplifier module 531 amplifies received signals RX2 a andRX2 b (seventh and ninth signals) respectively output from the front-endcircuits 141 a and 141 b and outputs amplified signals RX2 a_amp and RX2b_amp (sixth and seventh amplified signals). The low-noise amplifiermodule 531 includes filter circuits 600 a, 600 b, 601 a, and 601 b,amplifiers 610 a and 610 b, and a switch circuit 620. In thisembodiment, the filter circuits 600 a and 601 a, the amplifier 610 a,and a switch element 620 a form an amplification path for the receivedsignal RX2 a of the frequency band BAND_A, while the filter circuits 600b and 601 b, the amplifier 610 b, and a switch element 620 b form anamplification path for the received signal RX2 b of the frequency bandBAND_B. For the sake of simple representation, the other elementsforming the low-noise amplifier module 531 (such as a bias circuit and amatching circuit) are not shown in FIG. 12.

The filter circuits 600 a and 600 b allow the receive frequencycomponents of the received signals RX2 a and RX2 b to pass through thefilter circuits 600 a and 600 b and attenuate the other frequencycomponents. The filter circuits 600 a and 600 b may be band pass filtercircuits or low pass filter circuits, or may be high pass filtercircuits depending on the situation.

The amplifiers 610 a and 610 b (second and third low-noise amplifiers)respectively amplify the received signals RX2 a and RX2 b output fromthe filter circuits 600 a and 600 b, and respectively output amplifiedsignals RX2 a_amp and RX2 b_amp (sixth and seventh amplified signals).The amplifiers 610 a and 610 b may be constituted by MOSFETs orhigh-electron-mobility transistors (HEMTs) or bipolar transistors, suchas HBTs. The amplifiers 610 a and 610 b may be each constituted byplural stages of amplifiers.

The filter circuits 601 a and 601 b attenuate harmonics of the amplifiedsignals RX2 a_amp and RX2 b_amp and noise caused by the amplifiers 610 aand 610 b. The filter circuits 601 a and 601 b may be band pass filtercircuits or low pass filter circuits, or may be high pass filtercircuits depending on the situation.

The switch circuit 620 (fourth switch circuit) supplies only one of theamplified signals RX2 a_amp and RX2 b_amp in the two frequency bands tothe signal generating circuit 520, that is, the switch circuit 620performs control so that the two amplified signals RX2 a_amp and RX2b_amp will not be supplied to the signal generating circuit 520 at thesame time. The switch circuit 620 includes the switch elements 620 a and620 b. The switch elements 620 a_and 620 b_connect or disconnect thelow-noise amplifier module 531 to or from the signal generating circuit520 in the individual amplification paths. When one of the switchelements 620 a and 620 b is ON, the other one of the switch elements 620a and 620 b is OFF. When one of the amplified signals RX2 a_amp and RX2b_amp is supplied to the signal generating circuit 520, the other one ofthe amplified signals RX2 a_amp and RX2 b_amp is not supplied to thesignal generating circuit 520. It is thus less likely that a receivedsignal which may leak from one amplification path will be input into theother amplification path. That is, the isolation between theamplification paths of the received signals RX2 a and RX2 b can beenhanced.

The signal generating circuit 520 includes a synthesizer 630, amultiplier 640, a filter circuit 650, and an amplifier 660.

In a manner similar to the synthesizer 200 shown in FIG. 2, thesynthesizer 630 generates and outputs a local signal La (third referencesignal) (frequency fLa=about 10 GHz) and a local signal Lb (fourthreference signal) (frequency fLb=about 23 GHz) for generating the IFsignal IF2 from the received signals in the frequency band BAND_A andthe frequency band BAND_B.

The multiplier 640 combines the local signal La supplied from thesynthesizer 630 and the amplified signal RX2 a_amp supplied from thelow-noise amplifier module 531 so as to generate the IF signal IF2(eighth signal), and outputs it. Similarly, the multiplier 640 combinesthe local signal Lb supplied from the synthesizer 630 and the amplifiedsignal RX2 b_amp supplied from the low-noise amplifier module 531 so asto generate the IF signal IF2 (eighth signal), and outputs it.

The IF signal IF2 may be a signal of a frequency (about 5 GHz, forexample) which is lower than the frequency (about 15 GHz, for example)of the received signal RX2 (seventh signal) and which can be processedby the receive circuit 510 supporting the conventional modes. It is thuspossible to process the received signal RX2 of a new mode by using thereceive circuit 510 supporting the conventional modes, without providingan extra receive circuit for a new mode in the communication unit 500.

If the amplified signals RX2 a_amp and RX2 b_amp are not supplied to themultiplier 640, the synthesizer 630 and the multiplier 640 may be turnedOFF so that a local signal and an IF signal will not be generated. Thefrequencies of the signals generated by the multiplier 640 will bediscussed with reference to FIG. 13.

FIG. 13 illustrates an example of a state where the IF signal IF2 isgenerated from the amplified signals RX2 a_amp and RX2 b_amp and thelocal signals La and Lb. In a manner similar to the multiplier 210 shownin FIG. 2, the multiplier 640 outputs a signal of a frequencyrepresenting the sum of the frequencies of two signals and also outputsa signal of a frequency representing the difference between thefrequencies of the two signals. That is, if the amplified signal RX2a_amp and the local signal La (frequency fLa=about 10 GHz) are inputinto the multiplier 640, the multiplier 640 outputs signals including asignal MIX2 a _(UP) having a frequency fRX2 a+fLa=15+10=25 GHz and asignal MIX2 a _(DOWN) having a frequency fRX2 a−fLa=15−10=5 GHz. In thisembodiment, the signal _(MIX2) a _(DOWN) of about 5 GHz is used as theIF signal IF2, and the signal MIX2 a _(UP) of about 25 GHz is an imagesignal.

Similarly, if the amplified signal RX2 b_amp and the local signal Lb(frequency fLb=about 23 GHz) are input into the multiplier 640, themultiplier 640 outputs signals including a signal MIX2 b _(UP) having afrequency fRX2 b+fLb=28+23=51 GHz and a signal MIX2 b _(DOWN) having afrequency fRX2 b−fLb=28−23=5 GHz. In this embodiment, the signal MIX2 b_(DOWN) of about 5 GHz is used as the IF signal IF2, and the signal MIX2b _(UP) of about 51 GHz is an image signal.

Referring back to FIG. 12, the filter circuit 650 (third filter circuit)attenuates the above-described image signals MIX2 a _(UP) and MIX2 b_(UP). More specifically, among the signals generated by the multiplier640, the filter circuit 650 allows the frequency components of thesignals MIX2 a _(DOWN) and MIX2 b _(DOWN) to pass through the filtercircuit 650 and attenuates the frequency components of the signals MIX2a _(UP) and MIX2 b _(UP). For example, the filter circuit 650 may be aband pass filter circuit or a low pass filter circuit that allows thefrequency components of the signals MIX2 a _(DOWN) and MIX2 b _(DOWN)(about 5 GHz) to pass through the filter circuit 650 and that attenuatesthe frequency components of the signals MIX2 a _(UP) (about 25 GHz) andMIX2 b _(UP) (about 51 GHz) which are higher than the signals MIX2 a_(DOWN) and MIX2 b _(DOWN) (about 5 GHz) (see FIG. 13).

The amplifier 660 (fourth low-noise amplifier) is disposed subsequent tothe filter circuit 650. The amplifier 660 amplifies the IF signal IF2output from the filter circuit 650 and outputs an amplified signalIF2_amp (eighth amplified signal). The amplifier 660 amplifies power ofthe IF signal IF2 attenuated by the insertion of the filter circuit 650.

The amplified signal IF2_amp output from the signal generating circuit520 is demodulated by the receive circuit 510.

With the above-described configuration, as in the generation of atransmit signal in the communication unit 100, the communication unit500 does not have to directly demodulate a received signal in afrequency band of a new mode, but demodulates the amplified signalIF2_amp generated by the signal generating circuit 520. By using thereceive circuit 510 supporting conventional modes, the communicationunit 500 is able to support a new communication standard (new mode)substantially without the need of additional components.

FIG. 14 illustrates another example of the configuration of thecommunication unit 500 (communication unit 500A) according to theembodiment. The communication unit 500A is different from thecommunication unit 500 shown in FIG. 11 in that it includes a switchelement 700 in addition to the elements forming the communication unit500.

The switch element 700 (third switch circuit) is disposed between thereceive circuit 510 and the signal generating circuit 520, and connectsor disconnects the receive circuit 510 to or from the signal generatingcircuit 520. More specifically, the switch element 700 is turned ON whenthe communication unit 500A receives a received signal in a frequencyband of a new mode, and the switch element 700 is turned OFF when thecommunication unit 500A does not receive a received signal in afrequency band of a new mode. It is thus less likely that, whenprocessing a received signal of a conventional mode and that of a newmode, a received signal of one mode will be input into the path of areceived signal of the other mode. The switch element 700 may bedisposed within a RFIC 505A, as shown in FIG. 14, or may be disposedoutside the RFIC 505A.

FIG. 15 illustrates another example of the configuration of thecommunication unit 500 (communication unit 500B) according to theembodiment. The communication unit 500B is different from thecommunication unit 500 shown in FIG. 11 in that it includes a receivecircuit 810, a low-noise amplifier module 830, a front-end circuit 340,and an antenna 350 corresponding to a received signal RX3 in a frequencyband of a conventional mode, in addition to the elements forming thecommunication unit 500.

The low-noise amplifier module 830 includes an amplifier (fifthlow-noise amplifier). The low-noise amplifier module 830 amplifies thereceived signal RX3 (tenth signal) in a frequency band of a conventionalmode received from the antenna 350 and outputs an amplified signalRX3_amp (ninth amplified signal).

The receive circuit 810 (second receive circuit) demodulates theamplified signal RX3_amp and outputs an output signal (second outputsignal), such as a sound or data signal.

The detailed configurations of the receive circuit 810, the low-noiseamplifier module 830, the front-end circuit 340, and the antenna 350 aresimilar to those of the receive circuit 510, the low-noise amplifiermodule 530, the front-end circuit 140, and the antenna 150 shown in FIG.11, and a detailed explanation thereof will be omitted.

With this configuration, too, by using the receive circuits 510 and 810supporting conventional modes, the communication unit 500B is able tosupport a new communication standard (new mode) substantially withoutthe need of additional components. The communication unit 500B, which iscapable of simultaneously receiving signals of multiple frequency bands,is applicable to a mobile terminal supporting carrier aggregation, forexample. The switch element 700 shown in FIG. 14 may also be used in thecommunication unit 500B. As shown in FIG. 15, the receive circuits 510and 810 may be included in a single RFIC 505B. Alternatively, thecommunication unit 500B may include plural RFICs, and the RFICs mayinclude the respective receive circuits 510 and 810.

FIG. 16 illustrates an example of the configuration of a communicationunit 800 according to an embodiment of the disclosure. As shown in FIG.16, in the communication unit 800, a front-end circuit 141 switchesbetween a path for a transmit signal and a path for a received signal.The front-end circuit 141 includes a switch circuit, for example, andsupplies a transmit signal output from a power amplifier module 131 toan antenna 151 or supplies a received signal output from the antenna 151to a low-noise amplifier module 531. A path for a signal output from aRFIC 105 including a transmit circuit and a path for a signal outputfrom a RFIC 505 including a receive circuit may also be switched by aswitch. For the sake of simple representation, only the path for a newmode is shown in FIG. 16. However, the configuration of thecommunication unit 800 is not restricted to this example. Although thesingle antenna 151 is shown, the power amplifier module 131 and thelow-noise amplifier module 531 may be connected to different antennas.

FIG. 17 schematically illustrates an example of the circuit arrangementon a communication device substrate 1000 on which a communication unitof an embodiment of the disclosure is mounted. The communication devicesubstrate 1000 shown in FIG. 17 has a communication unit of anembodiment mounted thereon, and transmits and receives RF signals with abase station.

As shown in FIG. 17, the communication device substrate 1000 includesantennas 150 and 151 a, front-end circuits 140 and 141 a, poweramplifier modules 130 and 131, and low-noise amplifier modules 530 and531. For the sake of simple representation, the other components formingthe communication device substrate 1000 are not shown in FIG. 17.

On the communication device substrate 1000, the distance of atransmission line from the input/output terminal of the antenna 150(first antenna) that transmits and receives signals of conventionalmodes to the output terminal of the amplifier (first amplifier) includedin the power amplifier module 130 or to the input terminal of theamplifier (first low-noise amplifier) included in the low-noiseamplifier module 530 is set to be d1. On the communication devicesubstrate 1000, the distance of a transmission line from theinput/output terminal of the antenna 151 a (second antenna) thattransmits and receives signals of a new mode to the output terminal ofthe amplifier (second amplifier) included in the power amplifier module131 or to the input terminal of the amplifier (second low-noiseamplifier) included in the low-noise amplifier module 531 is set to bed2.

The frequency of a RF signal in a frequency band of a new mode is higherthan that in a frequency band of a conventional mode, and insertion lossof the RF signal of a new mode is greater than that in a conventionalmode. The antenna 151 a, the power amplifier module 131, and thelow-noise amplifier module 531 are arranged on the communication devicesubstrate 1000 so that the distance d2 of the transmission line betweenthe antenna 151 a and the amplifier that amplifies a signal of a newmode will be shorter than the distance d1 of the transmission linebetween the antenna 150 and the amplifier that amplifies a signal of aconventional mode. It is thus possible to reduce loss of RF signals inthe transmission line from the power amplifier module 131 to the antenna151 a via the front-end circuit 141 a or the transmission line from theantenna 151 a to the low-noise amplifier module 531 via the front-endcircuit 141 a.

The exemplary embodiments of the disclosure have been discussed. In thecommunication units 100 and 100A through 100D, the transmit circuits 110and 110A generate the IF signal IF1, and the signal generating circuits120, 120A, and 120B generate the high-frequency transmit signals TX2 aand TX2 b based on the IF signal IF1 and the local signals La throughLe. This eliminates the need for the transmit circuits 110 and 110A todirectly generate high-frequency transmit signals of a new mode. Byusing the transmit circuits 110 and 110A supporting conventional modes,the communication units 100 and 100A through 100D are able to support anew communication standard (new mode) substantially without the need ofadditional components.

In the communication units 100 and 100A through 100E, the transmitcircuits 110, 110A, and 410 may output the transmit signal TX1 or the IFsignal IF1 from the same terminal. However, the configuration of thesignal output terminal is not limited to this example.

The communication unit 100A includes the switch element 300 disposedbetween the transmit circuit 110 and the signal generating circuit 120.It is thus less likely that, when processing a transmit signal of aconventional mode and that of a new mode, a transmit signal of one modewill be input into the path of a transmit signal of the other mode.

The conventional modes supported by the communication units 100 and 100Athrough 100E may be modes using frequencies in the IEEE C band (about 4to 8 GHz band) or lower bands, and a new mode supported by thecommunication units 100 and 100A through 100E may be a mode usingfrequencies in the IEEE X band (about 8to 12 GHz band) or higher bands.

In the communication units 100 and 100A through 100E, the poweramplifier module 131 includes the amplifiers 240 a and 240 b so as toform plural amplification paths for transmit signals in multiplefrequency bands of a new mode. This enables the communication units 100and 100A through 100E to support transmit signals in multiple frequencybands of a new mode.

In the communication units 100 and 100A through 100E, the poweramplifier module 131 includes the switch circuit 220 which stops oneamplification path when the other amplification path is operated. It isthus less likely that a transmit signal which may leak from oneamplification path will be input into the other amplification path. Thatis, the isolation between the amplification paths can be enhanced.

The communication unit 100B includes the transmit circuit 310, the poweramplifier module 330, the front-end circuit 340, and the antenna 350corresponding to a conventional mode, in addition to the elementsforming the communication unit 100. The communication unit 100B is thusable to simultaneously transmit signals of multiple frequency bands, andis applicable to carrier aggregation.

The signal generating circuit 120C includes an image rejection mixerthat generates frequency components representing the sum of thefrequencies of the IF signal IF1 and the local signal Lf and rejectsfrequency components representing the difference therebetween. Thesignal generating circuit 120C is thus able to reduce the influence ofnoise caused by the image signal to a smaller level than the signalgenerating circuit 120B.

In the communication unit 100E, the RF circuit 170B supporting awireless LAN generates the IF signal IF1. With this configuration, too,by using the transmit circuit 410 supporting a wireless LAN, thecommunication unit 100E is able to support a new communication standard(new mode) substantially without the need of additional components.

In the communication units 500, 500A, and 500B, the signal generatingcircuit 520 generates the IF signal IF2 based on the amplified signalsRX2 a_amp and RX2 b_amp and the local signals La and Lb. This eliminatesthe need for the receive circuit 510 to directly demodulate ahigh-frequency receive signal of a new mode. By using the receivecircuit 510 supporting conventional modes, the communication units 500,510A, and 510B are able to support a new communication standard (newmode) substantially without the need of additional components.

In the communication units 500, 500A, and 500B, the receive circuit 510may receive the amplified signal RX1_amp or the amplified signal IF2_ampfrom the same terminal. However, the configuration of the signal inputterminal is not limited to this example.

The communication unit 500A includes the switch element 700 disposedbetween the receive circuit 510 and the signal generating circuit 520.It is thus less likely that, when processing a received signal of aconventional mode and that of a new mode, a received signal of one modewill be input into the path of a received signal of the other mode.

The conventional modes supported by the communication units 500, 500A,and 500B may be modes using frequencies in the IEEE C band (about 4 to 8GHz band) or lower bands, and a new mode supported by the communicationunits 500, 500A, and 500B may be a mode using frequencies in the IEEE Xband (about 8 to 12 GHz band) or higher bands.

In the communication units 500, 500A, and 500B, the low-noise amplifiermodule 531 includes the amplifiers 610 a and 610 b so as to form pluralamplification paths for received signals in multiple frequency bands ofa new mode. This enables the communication units 500, 500A, and 500B tosupport received signals in multiple frequency bands of a new mode.

In the communication units 500, 500A, and 500B, the low-noise amplifiermodule 531 includes the switch circuit 620 which stops one amplificationpath when the other amplification path is operated. It is thus lesslikely that a received signal which may leak from one amplification pathwill be input into the other amplification path. That is, the isolationbetween the amplification paths can be enhanced.

In the communication units 500, 500A, and 500B, the signal generatingcircuit 520 includes the amplifier 660 disposed subsequent to the filtercircuit 650. The amplifier 660 can amplify power of the IF signal IF2attenuated by the insertion of the filter circuit 650.

The communication unit 500B includes the receive circuit 810, thelow-noise amplifier module 830, the front-end circuit 340, and theantenna 350 corresponding to a conventional mode, in addition to theelements forming the communication unit 500. The communication unit 500Bis thus able to simultaneously receive signals of multiple frequencybands, and is applicable to carrier aggregation.

The antenna 151 a, the power amplifier module 131, and the low-noiseamplifier module 531 are arranged on the communication device substrate1000 so that the distance of a transmission line between the antenna 151a and the amplifier that amplifies a signal of a new mode will beshorter than the distance of a transmission line between the antenna 150and the amplifier that amplifies a signal of a conventional mode. It isthus possible to reduce loss of high-frequency RF signals in thetransmission lines when transmitting and receiving the high-frequency RFsignals.

The above-described embodiments are provided for facilitating theunderstanding of the invention, but are not intended to be exhaustive orto limit the invention to the precise forms disclosed. Modificationsand/or improvements may be made without departing from the scope andspirit of the invention, and equivalents of the invention are alsoencompassed in the invention. That is, suitable design changes made tothe embodiments by those skilled in the art are also encompassed in theinvention within the scope and spirit of the invention. For example, theelements of the embodiments and the positions, materials, conditions,configurations, and sizes thereof are not restricted to those describedin the embodiments and may be changed in an appropriate manner. Theelements of the embodiments may be combined within a technicallypossible range, and configurations obtained by combining the elements ofthe embodiments are also encompassed in the invention within the scopeand spirit of the invention.

While preferred embodiments of the invention have been described above,it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the invention. The scope of the invention, therefore, isto be determined solely by the following claims.

What is claimed is:
 1. A communication unit comprising: a firstlow-noise amplifier that receives and amplifies a sixth signal and thatoutputs a fifth amplified signal, wherein the fifth amplified signal isamplified according to a third generation (3G) or a fourth generation(4G) communication standard; a second low-noise amplifier that receivesand amplifies a seventh signal and that outputs a sixth amplifiedsignal, wherein the sixth amplified signal is amplified according to afifth generation (5G) communication standard, the 5G communicationstandard including at least one frequency band that is higher than allfrequency bands of the 3G and 4G communication standards; a secondsignal generating circuit that generates an eighth signal, wherein theeighth circuit has a frequency lower than a frequency of the sixthamplified signal, and is based on the sixth amplified signal and a thirdreference signal; a third filter circuit that receives the eighth signaland outputs a filtered eighth signal by passing one of and attenuatingthe other of a frequency component representing a sum of the frequencyof the sixth amplified signal and a frequency of the third referencesignal, and a frequency component representing a difference between thefrequency of the sixth amplified signal and the frequency of the thirdreference signal; a first receive circuit that outputs a first outputsignal based on the fifth amplified signal or the filtered eighth signaloutput from the third filter circuit; and a third switch circuitdisposed between the first receive circuit and the second signalgenerating circuit, wherein the third switch circuit is turned ON whenthe eighth signal is output from the second signal generating circuit,and the third switch circuit is turned OFF when the eighth signal is notoutput from the second signal generating circuit.
 2. The communicationunit according to claim 1, wherein: the frequency of the sixth signal isequal to or less than a frequency in a C band; and a frequency of theseventh signal is equal to or greater than a frequency in an X band. 3.The communication unit according to claim 1, further comprising: a thirdlow-noise amplifier that receives and amplifies a ninth signal and thatoutputs a seventh amplified signal, wherein the second signal generatingcircuit generates the eighth signal, wherein the eighth circuit has afrequency lower than a frequency of the seventh amplified signal, and isbased on the seventh amplified signal and a fourth reference signal, andthe third filter circuit receives the eighth signal and outputs thefiltered eighth signal by passing one of and attenuating the other of afrequency component representing a sum of the frequency of the seventhamplified signal and a frequency of the fourth reference signal, and afrequency component representing a difference between the frequency ofthe seventh amplified signal and the frequency of the fourth referencesignal.
 4. The communication unit according to claim 3, furthercomprising: a fourth switch circuit that supplies either the sixthamplified signal or the seventh amplified signal to the second signalgenerating circuit.
 5. The communication unit according to claim 3,wherein a frequency of the ninth signal is equal to or greater than afrequency in an X band.
 6. The communication unit according to claim 1,further comprising: a fourth low-noise amplifier that receives andamplifies the eighth signal and that outputs an eighth amplified signal,wherein the first receive circuit outputs the first output signal basedon the eighth amplified signal.
 7. The communication unit according toclaim 1, further comprising: a fifth low-noise amplifier that receivesand amplifies a tenth signal and that outputs a ninth amplified signal;and a second receive circuit that receives the ninth amplified signaland that outputs a second output signal based on the ninth amplifiedsignal, wherein a frequency of the tenth signal is equal to or less thana frequency in a C band.
 8. The communication unit according to claim 1,further comprising: a communication device substrate on which the firstand second low-noise amplifiers are mounted; and a first antenna thatreceives the sixth signal and a second antenna that receives the seventhsignal, wherein the first antenna and the second antenna are mounted onthe communication device substrate, wherein, on the communication devicesubstrate, a distance of a transmission line between an input terminalof the second low-noise amplifier and an output terminal of the secondantenna is shorter than a distance of a transmission line between aninput terminal of the first low-noise amplifier and an output terminalof the first antenna.
 9. The communication unit according to claim 1,wherein the communication unit supports carrier aggregation.
 10. Thecommunication unit according to claim 9, wherein the carrier aggregationsupports the 4G communication standard and the 5G communicationstandard.
 11. The communication unit according to claim 10, wherein thecarrier aggregation supports both 4G communication standards.